77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
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/*
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(c) Copyright 2017 Michael R. Neilly
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the names of the copyright holders nor the names of their
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <fenv.h>
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/* This implementation is intended to comply with the following
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* specification:
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*
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* http://pubs.opengroup.org/onlinepubs/009695399/functions/feholdexcept.html
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* Referred to as 'feholdexcept.html below.
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*
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* "The feholdexcept() function shall save the current floating-point
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* environment in the object pointed to by envp, clear the
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* floating-point status flags, and then install a non-stop (continue
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* on floating-point exceptions) mode, if available, for all
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* floating-point exceptions."
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*/
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int feholdexcept(fenv_t *envp)
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{
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#if __riscv_flen
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/* Store the current FP environment in envp*/
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fenv_t fcsr;
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asm volatile("frcsr %0" : "=r"(fcsr));
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*envp = fcsr;
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/* Clear all flags */
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asm volatile("csrrc zero, fflags, %0" : : "r"(FE_ALL_EXCEPT));
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/* RISC-V does not raise FP traps so it is always in a "non-stop" mode */
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/* Per 'feholdexcept.html:
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*
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* "The feholdexcept() function shall return zero if and only if
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* non-stop floating-point exception handling was successfully
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* installed."
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*/
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#endif
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return 0;
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}
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